From the press release found at Library Technology Guides, "The Orange County Library System in Florida is providing iPhone access to its library catalog using Innovative's AirPAC product. A test-group of library users is now using iPhones to search the catalog, request items, and renew checked-out materials. This new capability launched in January 2009 as a development partnership between OCLS and Innovative. "
Check out the great promotional video they did, paying special attention to the excellent editing that makes the whole thing look as lightning-fast as the Apple commercials do ;-) But seriously, it's a good commercial.
You can try the site yourself at http://m.ocls.info/